This invention generally relates to splices as may be applied to flexible elastomeric articles, and more particularly to a unit splice configuration for splicing a floating roof tank secondary seal into a continuous annular sealing ring.
Floating roofs for large storage tanks which hold volatile liquid products are well known and understood in the art as are the seals that close up the free space between the floating roof and the vertical tank wall. These seals generally comprise a primary seal that is attached to the periphery of the floating roof and which reacts with the tank wall to centrally locate the roof within the confines of the tank while also providing a sliding seal conforming to the wall surface as the liquid level in the tank changes. A secondary seal is also provided which is generally referred to as a "weather seal" because it is designed to protect the more complicated primary seal from contamination by foreign material such as dirt, dust, water, snow and ice, and the like. The secondary seal is usually therefore located above the primary seal and is mounted in a manner to also conform to the tank wall as the floating roof moves in response to changing liquid levels. Primary and secondary sealing techniques and configurations of the type alluded to are described in the prior art as exemplified by the U.S. patents to A. H. Nelson (No. 3,338,454), Wardell et al (No. 4,099,643), and R. A. Bruening (No. 4,126,243).
Secondary seals currently in use come in a variety of arrangements and generally comprise a configuration of elastomeric and/or polmeric materials which may or may not include an embedded reinfocement material. Because of the large circumferencial extent of floating roof type tanks, the seals are made up of a plurality of seal strip lengths which are spliced together to form the substantially annular seal ring when mounted to the roof structure. Conventionally, the seal strips are butt joined and the joint is cemented and covered over with a ply of reinforcement material. This procedure has resulted in misalignment of the spliced butt ends which affects the sealing integrity of the annular secondary seal as it attempts to conform to the inner wall of the tank.
This invention therefore is directed to a splice configuration for floating roof secondary seals that may be factory fabricated in various lengths according to the width of the seal material to be spliced, applied in the field, and air cured or vulcanized to provide an integrally spliced secondary seal.
An aspect of one object of the invention is to provide a splice for floating roof tank secondary seals that facilitates proper alignment of the spliced seal strips such that the completed annular seal more closely conforms to the inner tank wall to effect a proper seal therebetween.
The invention therefore provides an integrally vulcanized splicing unit for connecting ends of seal material such as to create an annular seal ring comprising:
a first reinforced elastomeric ply strip having a central longitudinal axis and a length substantially greater than its width and juxtaposed to the first ply strip such that the longitudinal axes are algned in a vertical plane; and
an unreinforced elastomeric gum interposed between the first and second ply strips for the length thereof and having a width less than the widths of the ply strips and centrally positioned between the ply strips along their longitudinal axes such as to form a unit having an H-section configuration with length-wise slots on either side thereof for receiving the ends of the seal material therein.